Centrifugal pump for handling of liquid chlorine

Abstract

A machine for pumping liquid chlorine employs an upright shaft sump pump which is confined in a hermetically sealed housing and has a tubular supporting element surrounding the pump shaft. The latter is mounted in overhung position and is adjacent to a pressure pipe which conveys the pressurized liquid. The shaft seal is kept out of contact with the liquid by the housing as well as by a body of inert gas which is supplied to the interior of the housing and to the space between the shaft and the tubular element at a pressure depending on the pressure of inflowing liquid chlorine and being sufficiently high to prevent the inflow of liquid chlorine into the housing and/or tubular element when the pump is idle. The main impeller on the pump shaft is made integral with an auxiliary impeller which constitutes a hydrodynamic shaft seal and prevents the flow of conveyed liquid chlorine into the tubular element from below.

We claim: 
     
       1. A machine for pumping liquids, particularly liquid chlorine, comprising a shaft sump pump mounted in a housing, the interior of which is hermetically sealed from the atmosphere, said pump having a rotary shaft mounted in an overhung position, the upper portion of said shaft adapted to be rotated by drive means positioned outside of said housing, a shaft seal provided about said rotary shaft outside of the hermetically sealed housing and out of contact with the pumped liquids, a tubular supporting element surrounding the portion of the shaft within said housing, inlet means for admitting liquids into said pump within said housing, a pressure pipe for evacuation of liquid and means for admitting a compressed inert gas into the interior of said housing and said supporting element at a pressure such that the liquid cannot penetrate into said housing and contact said shaft seal when the pump is idle. 
     
     
       2. The machine of claim 1, wherein said pump further includes a first impeller and an auxiliary impeller both mounted on and driven by said shaft. 
     
     
       3. The machine of claim 2, wherein said auxiliary impeller is installed downstream of the first impeller, as considered in the direction of liquid flow from said inlet means through said pump. 
     
     
       4. The machine of claim 3, wherein said auxiliary impeller constitutes a hydrodynamic shaft seal which eliminates the dynamic pump head and suction pressure and thus prevents the flow of pumped liquid into said supporting element. 
     
     
       5. The machine of claim 1, wherein said shaft is an upright shaft. 
     
     
       6. The machine of claim 5, wherein said supporting element spacedly surrounds said shaft and has an upper portion provided with at least one opening allowing for communication between the interior of said housing and the space surrounding said shaft within the confines of said supporting element. 
     
     
       7. The machine of claim 6, wherein said upper portion includes the upper third of said supporting element. 
     
     
       8. The machine of claim 1, wherein the inert gas is nitrogen. 
     
     
       9. The machine of claim 1, wherein said supporting element has an opening for admission of inert gas from the interior of said housing into the interior of said supporting element.